The present disclosure relates to universal drills that can be applied to implant surgery, bone drilling or metal drilling. More particularly, the present disclosure relates to drill bits, which are capable of decreasing friction for safer and more predictable results.
The insertion of dental implants commonly involves previous drilling and tapping procedures using multiple surgical implant drill bits of varying diameters for the conformation of an implant bed. The main purposes of the drilling, among others, are the fixation of the implant at the apical portion and/or at the lateral walls of the surrounding bone and the establishment of primary stability. Multiple surgical implant drill bits are used with the intention of avoiding excessive temperatures in the bone tissue that is being prepared for receiving a dental implant. However, regardless of the drilling technique, drilling materials, drill geometry or bone characteristics, some degree of thermal and mechanical injuries can occur.
During the drilling procedures, some temperature rises are due to friction of the drill in contact with surrounding bone tissue, such as bone walls or bone fragments. If the bone temperature is higher than 47° C. for 1 minute, human bone cells will show damage, necroses, apoptoses and be replaced by connective tissue. This will not result in the necessary biologic stability for long term implant success. A certain amount of mechanical or primary stability is needed instantaneously after surgery. This primary stability depends on the bone quality and quantity, the implant threads and implant body design and the implant bed preparation procedure. Therefore, the implant bed preparation executed with the specific implant drill bits needs to be as minimally invasive, accurate and precise as possible.
The thermal and mechanical damage which is produced by the drilling procedure has been associated with a combination of different variables including drill speed, feed rate, drill diameter, drill geometry, drill design, irrigation, drilling depth and drilling pressure.
Over seventy percent of all energy that is delivered by a drill, its surface and down hole equipment to drill an implant bed is lost through friction. Friction reducers, or as commonly referred to in the drilling industry, lubricants, can help to alleviate friction. The three problems that are common with the use of standard lubricants are compatibility, efficacy and biologic compliance. Although the simplest lubricant (sterile saline solution) is commonly used in implant surgery, its effect is limited due to the in-vivo environment and constraints that go hand-in-hand with working on the human body. Because lubricant is not fully successful in solving the issue due to its inherent limitations, the drill design should be altered to reduce the friction.
Every implant drill loses power through friction. This friction results from the operating surface of standard mechanical drill bits being in close contact to surrounding hard tissue. Operational efficiencies are tremendously hindered by only delivering a fraction of the energy that is placed into the well to drill, trip and complete. Friction is the function of the reactive forces that are a result of two bodies rubbing against each other. This is the rubbing of wear components at the surface of the rig, the sliding and rotation of drill string components and casing against bone formation. Down hole friction is polynomial where there are several drilling functions that can contribute to the increase in friction. The three main contributors (responsible for at least 95% of friction below the rotary table) are drilling torque, drilling drag and flowing pressure losses.
The two most important items for an implant drill bit are drilling torque and drilling drag. Drilling torque (angular friction) is generated when the drill bit is rotated while conducting drilling operations such as drilling ahead or back reaming During rotational drilling, drilling torque accounts for a majority of the energy lost through friction. If left unmitigated, drilling torque can bring the drilling process to a halt. When drilling torque approaches or exceeds the rig's rotary (top drive or rotary table) capability, the drilling process becomes very limited or even ceases if left unmitigated. The ability to rotate is necessary to break the static friction that exists between the drill bit-to-casing (Guided Surgery) or drill bit-to-bone. The inability to rotate effectively manifests at slower drilling rates and poor hole cleaning, which can lead to even higher friction, lost circulation and stuck drills. Also rotating the drill bit continuously at higher torque can lead to more frequent surface equipment failures, down hole equipment failures, casing wear and drill bit failures. Drilling drag (axial friction) is generated as the drill bit slides against the surrounding material formation or casing.
Therefore, there is a need for improved implant drill bits to achieve decreased friction for safer and more predictable and precise implant bed preparations in patients' bones, while also decreasing the time required to complete the preparation by decreasing the number of surgical drill bits needed.